1. Field of the Invention
This invention relates to lubricating devices and more particularly to series spool valve lubricant feeders.
Cyclical lubricant feeder spool valve assemblies have been used for providing lubricant to a plurality of individual lubricant needing portions of a general assembly for some period of time. Such cyclic lubricant feeder spool valve assemblies are frequently used in large machine assemblies, including transfer lines, machine tools and machine clusters. In such embodiments, there are frequently a number of individual points which periodically must be provided with measured quantities of lubricant.
One known type of lubricant feeder shown, for example, in Porter et al U.S. Pat. No. 3,298,460 and Snow et al U.S. Pat. No. 4,312,425, the teachings of which are herein incorporated by reference, employs a valve block having a plurality of individual spool valves received in valve bores. The spool valves are cyclically shuttled between the ends of the valve bores and during each movement dispense a measured quantity of lubricant from their end chambers, i.e., the area between the end of the bore and the full diameter end of the spool valve. Such devices continue to cycle, with the valves moving in sequence, as long as lubricant is supplied to the valve block. Because the spool valves may be of differing size, different points needing lubrication can be supplied with different quantities of lubricant.
This type of device, known as a single line system, employs only a supply line from a lubricant source. All of the lubricant supplied from a prime source (which can be a prior feeder) is distributed within the valve block assembly to individual outlet lines to the machine parts needing lubrication.
Another type of lubrication system commonly in use is a loop system where a closed lubricant loop is utilized. Along the loop, various lubricant dispensing devices may be provided. Different types of loop systems are utilized, including continuous flow loops where the lubricant undergoes a continuous flow in one direction within the loop, and reversing flow loops, where lubrication begins from a lubricant source, is flowed through the loop and through the individual lubricant dispensers, back to the lubricant source. When pressure is received back at the lubricant source, indicating that the lubrication has flowed through the entire loop, the lubricant source reverses flow in the line. This type of loop allows each of the lubricant utilizers to be equipped with dispensing actuated bypasses. That is, each lubricant utilizer, whether it is a single line lubricant dispenser or a multiple line lubricant dispenser, when it has dispensed its predetermined quantity of lubricant, automatically activates a bypass bypassing the remaining lubricant in the loop onto the next lubricant utilizing device. Such lubricant utilizing devices frequently employ spool valves.
Another type of loop system utilizes cyclic series spool valves as the individual lubricant dispensing devices points in a loop line. Such devices make use of series spool valves arranged in a cascade or ladder arrangement. In such ladder arrangements, the lubricant from the loop is ported directly to an end chamber of a valve bore biasing the spool to the other end of the bore to dispense a quantity of lubricant stored in the end chamber at the said other end. The loop line supplied lubricant then spills over, or cascades, from the first end chamber to the end chamber of the next valve bore in the series to push over that valve bore's spool before again cascading or spilling down to the next of the valve bores in the series. When the last of the spools has been shunted, a port will open opening the last of the valve bore's end chamber to the outlet from the valve block back into the loop line.
Reverse flow of lubricant in the loop has the same effect on the other side of the valve bores and again cascades from the first valve bore's end chamber through to the last valve bore's end chamber then to the loop line. This type of system has a distinct advantage over other loop systems in that it allows each lubricant using device in the loop to supply measured quantities of lubricant to a large number of individual lubricant needing areas. For example, in a transfer line, a series valve feeder assembly could be used to supply all of the lubricant needing areas of a given cell on the transfer line with the loop line supplying the entire multicelled transfer line. In such instances, it may be necessary to supply lubricant to a large number of individual lubricant needing areas at each cell. A disadvantage, however, of the cascade or ladder type of lubricant dispenser is that the lubrication must pass through an end section of each of the spool bores in each valve block assembly.
Cyclic lubricant valve block assemblies not utilizing the cascade or ladder system are known which, instead of a cascade, provide lubricant to each of the valve bores in the valve block assembly from a common central feed line that connects to each of the valve bores in the assembly by branch passages. This feed line allows the lubricant to flow to the last of the spool valve bores without the necessity of passing through each of the proceeding spool valve bores in the individual assembly. Such "feed line" feeders have not heretofore been used in reverse flow loop.
It would be an advance in the art if feed line cyclical spool valve lubricant feeder assemblies could be used in reversing flow loop lubrication systems.